1. Field of the Invention
The present invention relates to a microfilm search method and device which searches a desired frame by determining the presence of frames from a density change in microfilm running direction.
2. Description of the Related Art
In a known microfilm search method, search marks (blips) are photographed or recorded besides the frames on microfilm and used as reference marks. The blips of microfilm during running are read and counted, and the blip count is used to identify frame addresses when a specific frame is sought. On the other hand, there is proposed a search method in which, instead of using the blips, the presence of frames is detected directly, and a desired frame is searched for from a sequence of detected frames.
Frames may be incorrectly detected, if frame edges are not aligned, or if dust sticks to the microfilm. Moreover, in a case where there is only a small difference in density between the frame on which document or image is photographed and a peripheral portion surrounding the frame, the frame cannot be accurately detected. If the frame is incorrectly detected or cannot be detected in this manner, the desired frame cannot be searched for correctly.